References of "Nys, Gilles-Antoine"
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See detailFrom consistency to flexibility: A simplified database schema for the management of CityJSON 3D city models
Nys, Gilles-Antoine ULiege; Billen, Roland ULiege

in Transactions in GIS (2021)

The use of 3D city models is now common practice; many large cities have their own digital model. Resilient and sustainable management of these models is necessary in many cases, where an application ... [more ▼]

The use of 3D city models is now common practice; many large cities have their own digital model. Resilient and sustainable management of these models is necessary in many cases, where an application could evolve over its lifecycle. The complexity of generic modeling standardization is often a limitation for a light and user-friendly usage and further developments. This article aims to propose an alternative, providing a simplified database schema implemented in document-oriented storage. Thanks to the use of the NoSQL store, the focus is on flexibility of the data schemas and thus its clarification. In order to aim attention at the compactness in web development, CityJSON has been chosen for the encoding of the 3D city models. Finally, a full-stack application (persistent storage, consistent edition, and visualization of 3D city models) has been developed to handle the simplified schema and illustrates its capabilities in two practical use cases. [less ▲]

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See detailAn extension of CityJSON for the support of point clouds
Nys, Gilles-Antoine ULiege

Conference (2021, July 06)

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See detailAn extension of CityJSON to support point clouds
Nys, Gilles-Antoine ULiege; Kharroubi, Abderrazzaq ULiege; Poux, Florent ULiege et al

in International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences (2021, June 30), XLII-B4-2021

The combination between dense point clouds and 3D vector objects permits new cartographic representation of urban information. This paper proposes an extension for the CityJSON encoding to support point ... [more ▼]

The combination between dense point clouds and 3D vector objects permits new cartographic representation of urban information. This paper proposes an extension for the CityJSON encoding to support point clouds. Following the 3.0 CityGML specifications, attributes and features are added to the core module of v1.0.1 CityJSON. Two solutions are proposed: inline complex geometries and external link to a remote file. The extended schema can be illustrated in four scenarios: detailed features visualization, fall-back solution in features reconstruction processes, simulating urban climate represented as vector fields, and true-to-life representation solution for complex elements such as solitary vegetation objects. It permits 3D city modelers to handle points clouds in a native way reducing files size and avoiding redundancy. All developments and documentation are available open-source. [less ▲]

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See detailPotential of green roofs in the East bank of Liege, Belgium
Joshi, Mitali Yeshwant ULiege; Rohon, Simon; Nys, Gilles-Antoine ULiege et al

Scientific conference (2021, March 30)

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See detail3D Variables Requirements for Property Valuation Modeling Based on the Integration of BIM and CIM
El Yamani, Siham ULiege; Hajji, Rafika; Nys, Gilles-Antoine ULiege et al

in Sustainability (2021), 13(2814),

Abstract:The growing rate of urbanization and vertical urban development has aroused the sig-nificance of geo-related variables for property units disposed vertically within the same building.Among these ... [more ▼]

Abstract:The growing rate of urbanization and vertical urban development has aroused the sig-nificance of geo-related variables for property units disposed vertically within the same building.Among these, 3D indoor physical and outdoor environmental variables are impacting the propertyvalue for each building unit. However, in the literature, the identified 3D variables, by using hedonicpricing models (HPM) for property valuation, are mainly restricted to 3D visualization. Their usein 3D simulation for an accurate evaluation of the property value is still limited. Furthermore,their value is often defined for a specific valuation purpose (e.g., taxation). This paper aims toinvestigate 3D variables with a significant impact on property value, to combine them with 3Dtechnical requirements and to be integrated in a future valuation model. Moreover, their 3D spatialand non-spatial elements are analyzed to identify which variables can be provided from 3D citymodels and building scale elements. To accomplish this, the potential of 3D building informationmodeling (BIM) and city information modeling (CIM) in property valuation is examined. Fromindoors; BIM/IFC (Industry Foundation Classes) models are the main data sources for structuraland living quality variables. While from outdoors, environmental variables and the surroundingbuilding’s information are provided from 3D city models (CityGML) [less ▲]

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See detailNew OGC 3D standards in urban built environment
Nys, Gilles-Antoine ULiege

Scientific conference (2020, October 27)

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See detailNew 3D standards and perspectives
Nys, Gilles-Antoine ULiege; Billen, Roland ULiege

Scientific conference (2020, September 22)

Presentation of the last developments of the 3D Standard of the OGC Family: CityGML 3.0 and CityJSON.

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See detailUliège activities related to CityJSON
Nys, Gilles-Antoine ULiege

Scientific conference (2020, September 17)

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See detailCityJSON Building Generation from Airborne LiDAR 3D Point Clouds
Nys, Gilles-Antoine ULiege; Poux, Florent ULiege; Billen, Roland ULiege

in ISPRS International Journal of Geo-Information (2020), 9(521),

The relevant insights provided by 3D City models greatly improve Smart Cities and their management policies. In the urban built environment, buildings frequently represent the most studied and modeled ... [more ▼]

The relevant insights provided by 3D City models greatly improve Smart Cities and their management policies. In the urban built environment, buildings frequently represent the most studied and modeled features. CityJSON format proposes a lightweight and developer-friendly alternative to CityGML. This paper proposes an improvement to the usability of 3D models providing an automatic generation method in CityJSON, to ensure compactness, expressivity, and interoperability. In addition to a compliance rate in excess of 92% for geometry and topology, the generated model allows the handling of contextual information, such as metadata and refined levels of details (LoD), in a built-in manner. By breaking down the building-generation process, it creates consistent building objects from the unique source of Light Detection and Ranging (LiDAR) point clouds. [less ▲]

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See detailAutomatic 3D Buildings Compact Reconstruction from LiDAR point clouds
Nys, Gilles-Antoine ULiege; Billen, Roland ULiege; Poux, Florent ULiege

in International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences (2020, August 12), (XLIII-B2-2020), 473-478

Point clouds generated from aerial LiDAR and photogrammetric techniques are great ways to obtain valuable spatial insights over large scale. However, their nature hinders the direct extraction and sharing ... [more ▼]

Point clouds generated from aerial LiDAR and photogrammetric techniques are great ways to obtain valuable spatial insights over large scale. However, their nature hinders the direct extraction and sharing of underlying information. The generation of consistent large-scale 3D city models from this real-world data is a major challenge. Specifically, the integration in workflows usable by decision-making scenarios demands that the data is structured, rich and exchangeable. CityGML permits new advances in terms of interoperable endeavour to use city models in a collaborative way. Efforts have led to render good-looking digital twins of cities but few of them take into account their potential use in finite elements simulations (wind, floods, heat radiation model, etc.). In this paper, we target the automatic reconstruction of consistent 3D city buildings highlighting closed solids, coherent surface junctions, perfect snapping of vertices, etc. It specifically investigates the topological and geometrical consistency of generated models from aerial LiDAR point cloud, formatted following the CityJSON specifications. These models are then usable to store relevant information and provides geometries usable within complex computations such as computational fluid dynamics, free of local inconsistencies (e.g. holes and unclosed solids). [less ▲]

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See detailPotential for urban greening with green roofs: A way towards smart cities
Joshi, Mitali ULiege; Selmi, Wissal ULiege; Binard, Marc ULiege et al

Scientific conference (2020)

Cities are experiencing increased pressure on social, economic, and environmental sectors due to the rapid urbanisation and increasing risk owing to climate change affecting the urban environment ... [more ▼]

Cities are experiencing increased pressure on social, economic, and environmental sectors due to the rapid urbanisation and increasing risk owing to climate change affecting the urban environment. Solutions such as green roofs are often discussed in the context of smart and sustainable cities as they present a multi-functional and solution-oriented approach to address these challenges. Green roofs become extremely relevant in the context of highly urbanised and compact cities where impervious surfaces are abundant. Therefore, in this paper, we analyse the potential of green roofs at a city scale with the help of parameters such as area and slope of the roof and structure of the building. We also identify the priority zones based on environmental and socio-economic parameters. The study is carried out in the city of Liege, Belgium. The results suggest that around 20% (350 hectares) of the total buildings in the city have the potential for developing green roofs. Moreover, the potential of green roofs is quite significant in terms of roof area in the priority zone. Due to significant socio-economic deprivation in high priority zones, implementation of green roofs might not be affordable. Buildings with larger roof sizes are mostly owned by ompanies or commercial establishments, thus, making larger roofs more relevant for retrofitting green roof. Thus, our approach can act as a preliminary decision-making tool for urban planners to analyse the potential of green roofs and prioritize them in deprived areas. [less ▲]

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See detailEO_Regions_Science: Basic Research in support of EO_Regions!
Orban, Anne ULiege; Barbier, Christian ULiege; Billen, Roland ULiege et al

Conference (2019, November 28)

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See detailIntegration of multiple sensor data into a 3D GIS for cities monitoring
Kasprzyk, Jean-Paul ULiege; Nys, Gilles-Antoine ULiege; Billen, Roland ULiege

Conference (2019, October 18)

This research is part of a larger project, called “Ecocity Tools”, which aims to establish environment and energy diagnostics for cities at the neighborhood scale. Experts in different fields provide ... [more ▼]

This research is part of a larger project, called “Ecocity Tools”, which aims to establish environment and energy diagnostics for cities at the neighborhood scale. Experts in different fields provide information based on both scientific models (climatology, pollutant dispersions) and sensor data (energetic cadaster, air quality) to a 3D GIS for decision support in urban planning. This paper focuses on two interconnected problematics about the use of GIS in a “Smart City” approach: an appropriate 3D geometric model and the integration of sensor data into this model. As buildings can be equipped by several sensors in multiples locations (rooms, floors, walls, etc), information should be attachable to specific geometric parts (like walls). It is thus important for 3D city models to be adapted to detailed scale levels. Thanks to the consideration of different levels of details (LoD), from buildings footprints (LoD 0) to interiors (LoD 4), the CityGML standard (OGC) can theoretically fit any 3D application. Nevertheless, these data are not always available at very detailed levels. For example, Belgian authorities deliver open data in CityGML LoD 2 (representing buildings as volumes with simplified roof shapes) for important cities like Brussels or Namur. Therefore, this paper proposes a PostGIS data model able to attach information to specific building parts even in poorly detailed city models (LoD 1 or 2). The second part of this research is the implementation of other OGC standards specifically for the visualization of sensor data into a GIS: Sensor Observation Service (SOS) and SensorThings API (STA). As Web Feature Service (WFS) does for geographical features, SOS allows any compatible GIS client to import georeferenced sensor data and metadata through a simple http request (including filters on space, time and other attributes). More recently, STA, in addition to SOS functions, supports JSON format for data exchanges and also provides a “Tasking Part”: the STA server is able to ask sensors and actuators to do specific tasks like “start/stop measurements”. In this research, a SOS server, able to communicate with the 3D GIS, is implemented thanks to the open source tool provided by 52North. [less ▲]

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See detailA Semantic Retrieval System for Remote Sensing Web Platforms
Nys, Gilles-Antoine ULiege; Kasprzyk, Jean-Paul ULiege; Hallot, Pierre ULiege et al

Conference (2019, June 13)

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See detailA Semantic Retrieval System for Remote Sensing Web Platforms
Nys, Gilles-Antoine ULiege; Kasprzyk, Jean-Paul ULiege; Hallot, Pierre ULiege et al

in International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences (2019, June 05), XLII-2(W13), 1593-1599

This paper proposes a solution to reduce the semantic gap between final users and data/processing providers in a web market place dedicated to remote sensing products. Nowadays, search engine are common ... [more ▼]

This paper proposes a solution to reduce the semantic gap between final users and data/processing providers in a web market place dedicated to remote sensing products. Nowadays, search engine are common tools on the Internet. Users are accustomed to use them and used to get tabular classification of provided answers. These smart agents are set up to answer basic questions using automatic pages redirection or chitchat. In this research, to ensure coherence between user’s requests and platform answers, natural language processing algorithms and knowledge graphs are integrated within a web platform thanks to a NoSQL graph database connected to open thesauri and Geographic Information Systems (GIS). Therefore, the most pertinent services can be proposed based on input sentences including non-technical vocabulary but also geographical components (the user interface includes a text area and an interactive map). While processing chains and remote sensing ontologies were presented in one of our previous studies, this article focuses on natural languages algorithms and knowledge mining. [less ▲]

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See detailGIS 3.0 : Towards a new generation of Geographic Information Systems
Nys, Gilles-Antoine ULiege

Conference given outside the academic context (2019)

New problems need new solutions. In a world where spatial data are not only a resource but also a product, Geographical Information Systems do have a role. This presentation will develop avenues for ... [more ▼]

New problems need new solutions. In a world where spatial data are not only a resource but also a product, Geographical Information Systems do have a role. This presentation will develop avenues for reflection in order to best meet the new challenges that arise. [less ▲]

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See detailSpatio-temporal reasoning in CIDOC CRM: an hybrid ontology with GeoSPARQL and OWL-Time
Nys, Gilles-Antoine ULiege; Van Ruymbeke, Muriel ULiege; Billen, Roland ULiege

in CEUR Workshop Proceedings (2018, October 13), 2230

Semantic description of cultural heritage information is already widely structured through CIDOC CRM and its different extensions. This shared understanding of cultural heritage information has already ... [more ▼]

Semantic description of cultural heritage information is already widely structured through CIDOC CRM and its different extensions. This shared understanding of cultural heritage information has already proved its usefulness. Until now, despite its spatial and temporal data management proposition, lack standardization limited the possibilities in terms of reasoning and workability. This paper proposes to increase the potentiality offered by the current scheme by including GeoSPARQL and OWL-Time in the framework. The result, as hybrid ontology, allows concurrent spatial and temporal handling. These are used to provide a near-full data management for complex spatio-temporal reasoning and querying through SPARQL queries. Example queries depicting the strength of the approach and allowing knowledge discovery in huge archaeological datasets illustrate its benefits [less ▲]

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See detailTOWARDS AN ONTOLOGY FOR THE STRUCTURING OF REMOTE SENSING OPERATIONS SHARED BY DIFFERENT PROCESSING CHAINS
Nys, Gilles-Antoine ULiege; Kasprzyk, Jean-Paul ULiege; Hallot, Pierre ULiege et al

in International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences (2018, September 19), XLII(4), 483-490

This paper proposes an ontology to structure and describe processing chains in the remote sensing field. These chains are made up of elementary elements (operations) organized in collections. The ... [more ▼]

This paper proposes an ontology to structure and describe processing chains in the remote sensing field. These chains are made up of elementary elements (operations) organized in collections. The collection notion, including information about order and repeatability of the elements, is widely defined by using the relations between their constituting items and relations to the whole data store. Applications of the ontology are illustrated with web services provided by a platform for users and providers of processing chains. A graphical interface facilitates data integration in a RDF triple store. Thanks to the management of metadata (ISO19115-3), relevant information can be requested by intelligent search engines. Graph analysis, errors management and consistency rules are computed in order to gather coherent information from the different sources. Results of these analyses are then used by machine learning algorithms for new knowledge discovery. [less ▲]

Detailed reference viewed: 130 (37 ULiège)